Laminated fluoropolymer containing substrate and collapsible dispensing container

ABSTRACT

There is disclosed a substrate of layers of materials comprising fluoropolymer layers having sandwiched therein between a metal foil layer and a paper layer all suitably adhered to one another. It is also contemplated that the substrate be employed in fabricating a dentifrice tube.

This application is a continuation of application Ser. No. 567,002,filed Dec. 30, 1983 now abandoned.

FIELD OF THE INVENTION

The present invention relates broadly to the container art. Theinvention is more particularly concerned with a collapsible dispensingcontainer of laminated wall construction in the body portion thereof,whereby product permeation and absorption, and oxygen absorption aresubstantially prevented in all regions of the container structuresusceptible thereto.

BACKGROUND OF THE INVENTION

Collapsible tubes formed of metallic and plastic materials have longbeen known in the packaging field. Extruded metal tubes are inherentlybrittle and repeated use not infrequently results in wall cracks so thatproduct is exuded from a location other than the essentially rigiddispensing orifice. Of the prior art metal tubes, aluminum tubes, whileprobably being the least brittle, are somewhat limited in theirapplications since up to the present time it has not been possible toapply to the interior surfaces thereof a completely satisfactorycoating, when required to prevent attack and corrosion of the metal byalkaline or acid contents and contamination of the contents by thereaction products. Notwithstanding the relatively brittle nature of ametal tube, the mentioned internal coating operation requires anadditional processing step which necessarily increases the cost of thefinal article.

Tubes formed of polyethylene and other plastic materials have enjoyedwide commercial success in the packaging of many products; however,certain other products after a time have been noted to deteriorate whencontained therein. Plastics as exemplified by polyethylene are permeableto a degree when employed in the wall thicknesses used in tubularcontainers, and the essential oils embodied in most dentifrices forflavoring purposes are reduced in volume during storage of thecontainer, rendering the dentifrice less palatable. Also, the plasticcontainer wall absorbs oxygen over a period of time and ultimately maydecompose the product, which has actually been found to be the case withfluoride-containing toothpastes.

It has accordingly been proposed to provide a relatively thin metallicfoil barrier between the product and the polyethylene tube body toprevent the mentioned loss of essential oils and the absorption ofoxygen. The metallic barrier has been suggested as an interlayer betweenfacing sheets of polyethylene, and that a laminate be formed by heatwith or without suitable adhesives. However, while a structure of thisgeneral character is effective to prevent some product permeation andoxygen absorption through the tube body, and particularly when the innerthermoplastic layer is a copolymer of an olefin and a polar groupcontaining monomer which is co-polymerizable therewith, there remainsthe possibility of product deteterioration albeit to a much lesserextent.

A disadvantage in a polyolefin surface resides in the inability of thesurface to readily receive printing or decorative material. In addition,polyolefin has a memory effect, that is, it does not remain compressedwhen squeezed; a particular disadvantage for dentifrice tubes. Tocounter such lack of compressibility the metal layer must be relativelythick so that its compressibility is imposed on the plastic.

SUMMARY OF THE INVENTION

It is, therefore, an important aim of the present invention to provide acollapsible dispensing container of laminated wall construction in thebody portion.

Another object of this invention lies in the provision of a tubularcontainer having a plurality of adherent layers in the body portionthereof, one of said layers providing a barrier to product migration andoxygen absorption such as a metallic foil and another of said layersbeing a material selected from the group consisting of a fluoropolymercontaining at least 40% by weight fluorine or copolymer or mixturethereof varying in density and crystallinity. The latter layer beinginnermost and preferably outermost with different additional laminaesandwiched therein between.

Such additional layers comprise paper and suitable adhesive and bondingagents such as copolymer of ethylene and acrylic acid. The collapsibledispensing container of the present invention may be constructed fromthe laminated substrate of the present invention by conventional andknown apparatuses. Exemplary of such equipment and method can bediscerned from U.S. Pat. No. 3,832,964, which is incorporated herein byreference.

A further object of the instant invention is to provide a method ofproducing laminated tubes in which a tubular body is formed of a barrierlayer and a fluoropolymer or copolymer thereof laminated thereto; thelaminated tube body is then located on a forming member in adjacency toa barrier member also positioned thereon.

Other objects and advantages of the invention will become more apparentas the description proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings wherein like numerals are employed to designate likeparts throughout the same:

FIG. 1 is a cross-sectional view of a fragmentary portion laminatedsubstrate of the present invention.

FIG. 2 is a side elevational view of a collapsible dispensing containerembodying the novel concepts of this invention, with portions of thebody walls being broken away to more fully illustrate the laminatedstructure.

Referring now first to FIG. 1 of the drawings, a substrate 10 is shownin cross-section whereby to reveal the components of the sandwich thatgoes to make up the laminated configuration.

It will be seen that the bottommost layer 11 is a fluoropolymer. Thesecond layer 12 thereabove is an adhesive layer which joins thefluoropolymer layer 11 with third layer 13 which is a metal foil such asaluminum foil. The fourth layer 14 is another adhesive that adhesivelysecures the other surface of the metal foil layer 13 to a paper layer15. The topmost layer 16 is fluoropolymer.

DETAILED DESCRIPTION OF THE INVENTION

The thermoplastic fluoropolymer of the present invention encompass suchpolymers as copolymer of hexafluoropropene and tetrafluoroethylene;tetrafluoroethylene; copolymer of heptafluoropropyl trifluorovinyl etherand tetrafluoroethylene; polychlorotrifluoroethylene and polyvinylidenefluoride.

The applicable fluoropolymers and use are disclosed in U.S. Pat No.3,194,428 and is incorporated by reference herein. Such copolymers madebe made by the method described in U.S. Pat. No. 2,549,935 and isincorporated by reference herein. They comprise 5-50% by weight ofhexafluoropropylene (preferably 5-15%) and 95-50% by weight oftetrafluoroethylene (preferably 95-85%) copolymerized, to form normallysolid resins which melt 20°-250° F.

These fluoropolymers are particularly useful because they have very lowflavor absorption characteristics as can be seen from the followingtables where fluoropolymers are compared with polyethylene where thethicknesses of the layers or coating are the same:

                  TABLE I                                                         ______________________________________                                        ABSORPTION OF FLAVOR FROM A DENTIFRICE PASTE                                  (Aging Condition: 1 Week at Room Temperature)                                                    Flavor Absorbed (%)                                        ______________________________________                                        Copolymer of hexafluoropropene and                                                                 0.2                                                      tetrafluoroethylene (Teflon FEP)                                              Tetrafluoroethylene (Teflon TFE)                                                                   0.3                                                      Copolymer of heptafluoropropyl                                                                     0.2                                                      trifluorovinyl ether and                                                      tetrafluoroethylene (Teflon PFA)                                              Polychlorotrifluoroethylene (Halar)                                                                0.4                                                      Polyvinylidene Fluoride (PVDF)                                                                     0.9                                                      Polyethylene         2.4                                                      ______________________________________                                    

                  TABLE II                                                        ______________________________________                                        ABSORPTION OF FLAVOR FROM A DENTIFRICE GEL                                    (Aging Condition: 2 Weeks at Room Temperature)                                                   Flavor Absorbed (%)                                        ______________________________________                                        Copolymer of hexafluoropropene and                                                                 0.1                                                      tetrafluoroethylene (Teflon FEP)                                              Tetrafluoroethylene (Teflon TFE)                                                                   0.2                                                      Copolymer of heptafluoropropyl                                                                     0.1                                                      trifluorovinyl ether and                                                      tetrafluoroethylene (Teflon PFA)                                              Polychlorotrifluoroethylene (Halar)                                                                0.2                                                      Polyvinylidene Flouride (PVDF)                                                                     0.1                                                      Polyethylene         1.0                                                      ______________________________________                                    

It is contemplated that within the purview of the invention theadhesives may be a copolymer of ethylene and acrylic acid or methacrylicacid, or sodium or zinc salts thereof in a diluent system.

The metal foil may be preferably aluminum foil.

The paper layer is desirably a kraft paper.

The thickness range of each of the layers is as follows:

Fluoropolymer layer 11 0.5 mils to 3.0 mils, preferably 1.0 mils

Adhesive layer 12--sufficient to assure adherence

Metal foil layer 13--0.5 mils to 2.0 mils, preferably 1.0 mils.

Adhesive layer 14--sufficient to assure adherence

Paper layer 15--1.5 mils to 2.5 mils, preferably 2.0 mils. Fluoropolymerlayer 16--3.5 mills to 5.0 mils, preferably 4.0 mils.

The topmost fluoropolymer layer 16 adheres to the paper layer 15 bymeans of the application of sufficient heat and pressure to thesubstrate. In the event the application of heat and pressure is notappropriate a suitable adhesive is to be employed. FIG. 2 is an exampleof the laminated structure of a collapsible container with the layersbeing demonstrated as in FIG. 1 with layer 11 being inner most and theother layer being of the same materials and in the same order as shown.

It is believed manifest from the foregoing that applicant has provided acollapsible container structure which substantially reduces the problemsheretofore unsolved by the prior art. The laminated substrate andlaminated shoulder piece 20 completely eliminates product permeation andoxygen absorption, and this highly desirable result is achieved by theuse of low cost materials which preferably are combined into laminatedform in the manner indicated in FIG. 2.

The outer layer of an fluoropolymer or copolymer thereof is athermoplastic capable of fusion during a side seaming step and grantingadequate protection to the paper and metallic foil interlayer. The artof seaming of a collapsible dentifrice tube of the general type hereindisclosed can be seen in U.S. Pat. No. 3,295,725, incorporated herein byreference.

However, the outer layer of fluoropolymer and paper may be eliminated ifthe foil barrier is of sufficient thickness to resist damage, and byflowing a thermoplastic material into the overlap side seam during thesealing thereof when such a system is employed.

Further, the outer layer may be paper in a three-ply laminate formed ofpaper, foil and an fluoropolymer and co-polymer thereof as described. Asthe outermost and innermost layers are preferably the same, the foldededges of the tube produced from the substrate in conveniently heatbonded. A suitable adhesive can be used when heat bonding is notpossible. This modification is in addition to the aforementionedfour-ply laminates comprised of from outside to in, fluoropolymer paper,foil and fluoropolymer, or fluoropolymer 20 foil, paper andfluoropolymer. It is contemplated that suitable adhesives will beemployed between the laminae whenever necessary. Like structures can beemployed for the shoulder piece, cap, neck, piston and in theconstruction of dispensing valves for such containers, particularly inconjunction with the interior portions exposed to the containeddentifrice, and, again, where required, compatible adhesives wouldnaturally be employed.

Various modifications of the invention have been disclosed herein, andthese and other changes can of course be effected without departing fromthe novel concepts of the instant contribution. Additionally when castas a film on the interior surfaces of fiber drums used for the storageof flavored dentifrice, the material will retard flavor loss into thedrums, thereby extending storage life.

What is claimed is:
 1. A collapsible paste dispensing container havinglow flavor absorption characteristics comprising a first innermost layerof a fluoropolymer, a second layer of metal foil, a third layer of paperand an outermost fourth layer of a fluoropolymer.
 2. The container ofclaim 1 wherein the fluoropolymer is a copolymer of hexafluoropropaneand tetrafluoroethylene.
 3. The container of claim 1 wherein thefluoropolymer is a tetrafluoroethylene.
 4. The container of claim 1wherein the fluoropolymer is a copolymer of heptafluoropropyltrifluorovinyl ether and tetrafluoroethylene.
 5. The container of claim1 wherein the fluoropolymer is a copolymer ofpolychorortrifluoroethylene and polyvinylidine fluoride.
 6. Thecontainer of claim 1 wherein the first layer of the fluoropolymer issecured to the metal foil with an adhesive.
 7. The container of claim 1wherein the third layer of paper is secured to the fourth layer of thefluoropolymer with an adhesive.
 8. A dispensing container according toclaim 1, wherein the low flavor absorption characteristics range fromabout 0.1 to about 0.9 percent.
 9. The container of claim 1 wherein thefirst layer of the fluoropolymer is secured to the metal foil with anadhesive and wherein the third layer of paper is secured to the fourthlayer of the fluoropolymer with an adhesive.
 10. The container of claim9 wherein the adhesive is a copolymer of ethylene and acrylic acid. 11.A substrate of layers of materials, which substrate has low flavorabsorption characteristics, comprising a first layer of a fluoropolymer,a second layer of metal foil, a third layer of paper, and a fourth layerof a fluoropolymer.
 12. The substrate of claim 11 wherein thefluoropolymer is a copolymer of hexafluoropropane andtetrafluoroethylene.
 13. The substrate of claim 11 wherein thefluoropolymer is a tetrafluoroethylene.
 14. The substrate of claim 11wherein the fluoropolymer is a copolymer of heptafluoropropyltrifluorovinyl ether and tetrafluoroethylene.
 15. The substrate of claim11 wherein the fluoropolymer is a copolymer ofpolychoratrifluoroethylene and polyvinylidine fluoride.
 16. Thesubstrate of claim 11 wherein the first layer of the fluoropolymer issecured to the metal foil with an adhesive.
 17. The substrate of claim11 wherein the third layer of paper is secured to the fourth layer ofthe fluoropolymer with an adhesive.
 18. The substrate of claim 11wherein the first layer of the fluoropolymer is secured to the metalfoil with an adhesive and wherein the third layer of paper is secured tothe fourth layer of the fluoropolymer with an adhesive.
 19. Thesubstrate of claim 18 wherein the adhesive is a copolymer of ethyleneand acrylic acid.